Myocardial ischemia–reperfusion (I/R) injury remains a critical contributor to cardiovascular morbidity and mortality. Phloretin, a natural dihydrochalcone derived from apples and pears, possesses potent antioxidant and anti-inflammatory activity. Yet, its direct cardioprotective action and underlying molecular mechanisms in isolated heart models have not been comprehensively elucidated. To investigate the cardioprotective efficacy of phloretin in an ex vivo rat heart model of I/R injury and to characterize its regulatory effects on apoptotic and pro-survival signaling pathways at the gene and protein levels.

Hearts from male Sprague–Dawley rats (n = 24) were perfused on a Langendorff system and exposed to 30 min global ischemia followed by 60 min reperfusion. Animals were allocated into three groups: Control (no treatment), phloretin 10 µM, and phloretin 50 µM (n = 8 each). Phloretin was administered during reperfusion. Cardiac functional indices—including left ventricular developed pressure (LVDP), heart rate, and coronary flow—were continuously recorded. Myocardial samples were analyzed by RT-qPCR for Bcl-2 and HSP70 gene expression, and by Western blotting for Bax, cleaved caspase-3, Akt, and p-Akt proteins. Statistical analysis was performed using one-way ANOVA with post-hoc testing.

Phloretin treatment significantly improved post-ischemic recovery of LVDP (65 ± 7% and 80 ± 6% for 10 µM and 50 µM vs 45 ± 5% in Control; p < 0.05 and p < 0.01, respectively). Upregulation of Bcl-2 (~1.5-fold and ~2.2-fold) and HSP70 (~1.3-fold and ~1.8-fold) was observed in a dose-dependent manner. Expression of pro-apoptotic proteins Bax and cleaved caspase-3 decreased, while the p-Akt/Akt ratio increased (~1.4 and ~2.0; p < 0.05), confirming activation of prosurvival pathways.

Phloretin confers substantial cardioprotection against ischemia–reperfusion injury by enhancing cardiac functional recovery, suppressing apoptosis, and promoting Akt-mediated survival signaling. These findings highlight phloretin’s therapeutic promise as a natural cardioprotective compound for ischemic heart disease.